Bucking bar control for riveting hammers



9 O E. WQSTEVENS 2,411,561 7 BUCKING BAR CONTROL FOR RIVE'I'ING HAMMERS 7 Filed Feb. 4, 1944 v 2 Sheets-Sheet l INVENTOR fan mm /1. JTEVi/VJ.

BYv v ATTORNEY 2 Sheets-Sheet 2 E. w. STEVENS Filed Feb. 4, 1944 NM w% x 15 BUCKING BAR CONTROL FOR RIVETING HAMMERS Nov. 26, 1946.

E hm g Q ATTO R N EY 1- 5:: @E Emma" m um mm mm Patented Nov. 26, 1946 BUCKING BAR CONTROL FOR RIVETING HAMMERS Edward W. Stevens, Detroit, Mich, assignor to Chicago Pneumatic Tool Company, New York, N. Y., a corporation of New Jersey Application February 4, 1944, Serial No. 521,028 (or. 78-48) 11 Claims.

This invention relates to riveting apparatus assemblies fundamentally comprising a fluid actuated tool and a bucking bar cooperating therewith to set rivets, and more particularly to certain features of automatic bucking bar remote control mechanism for said tool.

An object of the present invention is to introduce an improvement related to the copending application Serial No. 467,531 of James A. Rob-- erts, filed December 1, 1942 for Bucking bar control for riveting hammers, which has matured into Patent No. 2,375,691, granted May 8, 1945. The invention has a special but by no means exclusive application to aircraft riveting tools suitable for operation on light sheet metal.

The main object of this invention is therefore to facilitate riveting by providing a bucking bar mechanism for a fluid actuated riveting hammer or other tool having direct manual control, with improved means governing the height of the heads of the rivets to be set and operating automatically to stop the hammer when the predetermined height of a rivet has been produced.

Another very important object is to increase the, speed and uniformity of the riveting operation by providing adjustable accurate control of the hammer from the bucking bar mechanism in such manner as to produce uniformly set rivets with substantial elimination of damaged work.

It is also an object to haveassociated with a pneumatic hammer, a bucking bar mechanism or assembly provided with a member which not only governs the height of the heads of rivets to be set, but positively prevents production of too flat or small rivet heads even when the bucking bar is held adjacent to the work for an unusually long time.

Other objects and the advantages inherent in the invention and accruing'from its use in actual practice will appear more fully in detail as this specification proceeds.

The invention is illustrated in the accompanying drawings forming part hereof and in which: Fig. l is a side elevation of a fluid actuated hammer in operative position against a Work piece with a bucking bar mechanism operatively connected to the hammer and embodying cbntrol means for determining the height of the rivet heads intended to be set by the mentioned apparatus, portions of the apparatus being shown in section to disclose details of construction while the manual control lever is illustrated in active operating position; 7 r Fig. 2 is an enlarged side elevation, for the most part in section, showing the bucking bar mechanism with the manual control lever in initial starting position ready to initiate a cycle of operation;

Fig. 3*is an end view of the same device as seen from the right in Fig. 2;

Fig. 4 is also an enlarged elevation of the bucking bar mechanism similar to that of Fig. 2

but showing the manual control leverin operated position and in released or neutralized condition Fig. 5 is a transverse section of the mechanism of Fig. 4 as taken on line 5-5;

Fig. 6 is another transverse section of the same taken on line 6-6 in Fig. 4; and

Fig. 7 is a fragmentary perspective view of the manual operating lever of the same mechanism.

In the riveting artthe use of riveting assemblies of the present kind requires the services of two operators on opposite sides of the work who are occasionally hidden from each other, rendering each operator incapable of noting directly the movements of the other. In some assemblies used'before the invention of Roberts in the copending application, the throttle valve for the fluid supply was arranged to be under the control of a single operator, either the riveter or the bucker, who would usually delay commencement of the hammering operation until certain that the other operator was ready. Occasionally it then happened that the hammer was started before the rivet was properly backed up or before the hammer was inproper operative position, which in either case would likely result in damaged Work. I l

While the invention of said Roberts is designed to eliminate the mentioned disadvantages and facilitate the operation of setting a rivet to such an extent that it is unnecessary for theoperators engaged in the work to see each other or to observe any special precautions-in order. to produce satisfactory and rapid work, the present inven- I tion is directed to improved means for positively determining a uniform height of the heads of the rivets intended to be set.

It is, of course, self-evident that when a large number of rivets are tobe set, the time element involved is not onlyaffected by the speed of operation as ensured by effective cooperation between the two operators, but also by the uniformity in the height and-quality of the heads on the finished rivets. If some rivets are at first not sumciently set during operation, necessitating repeated operation to bring them to uniform height with the rest, time is lost, and if set too much, they are defective and damage has resulted.

The present invention is designed to ensure that at all times the heads of the rivets will be set to a uniform height.

Hence, referring again to the drawings, a riveting assembly comprises a pneumatic hammer, generally indicated at 8 of a type favored in the aircraft industry for setting small aluminumand' alloy rivets, The hammer assembly includes a cylinder 9 with an offset rigid handle iii and houses a fluid operated motor provided with a 'reciprocable piston H and means for directing pressure fluid alternately to the ends thereof, while the handle is formed with an air inlet port l2 and throttle means operating under the control of a trigger is. The piston ll acts as a hammer, delivering impacts to an anvil or rivet set M which extends beyond the front end of the cylinder for engagement with the work. The work or work piece, in this instance, is represented by a pair of overlapping plates generally indicated at l5 (hereinafter termed the work) which are fastened together by rivets to form part of an airplane skin covering. Guide holes are first provided in the work to receive rivets IS, the same being disposed with preformed heads contacting with the work l5 on one side thereof and having shank portions projecting through to the opposite side. According to one method of riveting, anvil or rivet set I4 is pressed against the preformed head on the rivet While the shank portion is engaged on the opposite side of the work and during operation set as shown at I! by a bucking bar it of a bucking mechanism generally indicated at l9. When the hammer is then started, percussive impulses are delivered to the work through the anvil l4 and are sustained by the bucking bar it. As forward pressure is exerted by the bucking bar throughout the operation the reaction of the hammer blows serves to upset the shank of the rivet, a flat or oval head being thereby formed on the side of the work opposite to that occupied by the preformed head.

It is important that the skin surface of the work be not marred or scratched by a premature hammer action. Thus care must be exercised by the separate operators holding the hammer and the bucking mechanism that the ends of the rivet are initially properly engaged before the hammer is started. As a matter of precaution, the apparatus is designed to guard against misoperation resulting from a lack of such engagement by placing the compressed air supply under the control of both the riveter and the bucker. The piston I I can therefore not begin reciprocation until the operators of the hammer and bucking bar mechanism signify by releasing the air supply that their respective implements are in effective working position. Important as the features just mentioned may be for proper operation, it should be noted that it is a prominent feature of the invention to make it wholly unnecessary for the bucker to observe any special care in order to produce a uniform height of rivet head on all rivets set when using the present bucking bar mechanism.

The air inlet port I2 is part of a pressure fluid supply pasageway including passages 29 and 2l communicating through a bore 22. Within said bore 22 is a bushing 23 having ports registering respectively with passages 29 and 2 I Communication between passages 29 and 2| is controlled by a trigger operated throttle valve 24 in bushing 23, said valve being pressed by a spring 25 to a seat 26 between the ported areas of the bushing and so normally prevents the flow of fluid to the passage 2! and thereby to the hammer cylinder. Valve 24 has a stem 2! extending upward through and beyond the bushing ,23, the upper end of the stem underlying one arm of a lever 28 which is pivotally mounted at 29 within a recess in the handle it and is operatively engaged with the trigger l3. When the trigger is shifted rearward by the pressure of the finger of an operator the lever 23, rocking upon its pivot 29 verse bore in said bar. and 41 in the respective split projections 33 and unseats valve 24, whereupon air from inlet port l2 and passage 20 is allowed to flow through bushing 23 and into passage 2| whence it flows to the motor to initiate operation of the hammer.

Air under pressure is supplied to the inlet port 12 through a fitting in the form of an auxiliary valve housing 30 introduced between the inlet port l2 and a hose line 3| to facilitate control of the operation of the hammer by means of the invention. The auxiliary housing 39 has a tubular portion 32 extending into the inlet port I2 in threaded connection with a bushing 33. The body of thesame housing 30 defines a cham ,ber 34 receiving air from the hose line 31 and communicating with the interior of tubular portion 32 by way of a passage 35. Controlling the flow of air from chamber 34 to passage 35 is an auxiliary throttle valve 36, which has a valve head 31 disposed within chamber 34 while the valve stem 38 thereof extends through passage 35 and into a split projection 39 on the housing. The head 31 of valve 36 is adapted to occupy or engage with avalve seat 49 on the peripheral edge of passage 35 and thereby cut off the flow of fluid from chamber 34 to tubular portion 32 and inlet port l2. lhe supply of air to the hammer is therefore under the dual control of the throttle valve 24 and the auxiliary valve 36, either or both of which when closed will cut off the supply of fluid from the motor and so prevent operation of the hammer. The two valves 24 and 36 are actually arranged in series and thus provide the dual control of the operation.

The opening of valve 35 is accomplished by remote control from the bucking bar l8 by means of a Bowden type flexible cable 4! extending between the hammer 8 and the bucking mechanism 19 and made up of a wound sheath 42 and an inner wire or core 43 slidable within said sheath. The cable at one end is received in the split projection 39 of housing 30 and at its other end extends through a similar split clamping projection 44 on the bucking bar fitting in a trans- Clamping screws 46 44 serve to clamp the ends of the cable within the two implements. The core 43 is movable longitudinally within its sheath and arranged with one end projecting beyond the sheath, where it is secured to the stem 38 of valve 36 by soldering, brazing or Welding. The other end of the same core projects upwardly in a counterbore 48 in the bucking bar and is capped by a plunger 49 secured thereto and located in said counterbore and normally projecting a short distance above the bucking bar. The counterbore 48 is of greater diameter than the bore 45 receiving the end of the cable sheath and forms a casing for a compression spring 5i surrounding the cable core beneath plunger 49 and tending to hold the latter resiliently in the raised initial position shown in Figs. 1 to 3 and causing a pull to be exerted on said cable core, thereby maintaining the auxiliary throttle valve in housing 39 normally closed.

The means included in th bucking bar mechanismor assembly for depressing the plunger and thereby opening the auxiliary throttle valve to allow pressure fluid to enter inlet port l2 from chamber 34 primarily consists of a manual operating lever 52 preferably formed of sheet metal of inverted U-shaped cross section with the sides 53, 53 bent down from the top web portion 54 and terminating in a pair of lugs 55 at the forward end thereof, pivotally mounted in a pair of opposit sid recesses 56 on a pivot pin 51 in the bucking bar l8. Within the sides 53, 53 of lever 52 is a movable escape or release slide member 58. This latter is made of a metal strip bent back on itself to form upper and lower slide strips 59, SI connected at oneend by a web portion 62 and shiftably mounted upon a pair of cross rods 63 in such fashion as to straddle the latter, the slide member 58 being slidable longitudinally within sides 53 and top 54 of said manual lever. To the rear or outer end E l of the manual lever 52 is fixed an interior guide rod 65 extending longitudinally forward in substantial parallelism with thetop and sides toward the pivoted end of the manual lever and projecting slidably into the rear end or web 62 of the release slide member through an aperture 66 and supporting a coil spring 6'! bearing against the rear end of said releaseslide member and thus tending to urge the latter forward. Upon the underside of the lever is fixed an inflexibl plate 68 serving to assist in retaining the release slide member in place and more definitely to press upon the upper end of a lever return plunger 69 located in a limited bore H in the bucking bar and provided with a compression spring 12 tending to raise said plunger against said lever plate and thereby raise the lever to normal starting position in which the plunger cap 49 upon the cable core 43 is also in normal raised position with the auxiliary throttle valve 36 closed.

In the lower strip H of the release slide member is an aperture or gap 13 which is adapted to register with the upper end of the cable cap as in a manner now to be explained. When the riveter or hammer operator has placed the hammer 8 in operative position against the head of a rivet it and then manually presses the trigger or plunger 13 and thereby opens the throttle valve 24, the hammer will not begin to operate until certain other conditions are also present.

When the bucker who handles the bucking mechanism is about to cooperate with the riveter to set a rivet, he places the end of the bucking bar l8 more or less accurately against the shank end of rivet l6. During this movement a sleeve 14 adapted to surround the rivet first engages against the work l and is resiliently retracted upon the bucking bar by pressure until the latter makes contact with rivet it in a manner and bucking bar against the rivet It, the first portion 7 of the bucking mechanism which will make contact with the work as already explained is the end of the sleeve 14, and although the latter projects a distance beyond the working end 75 of the for a purpose now to be explained. The mentioned sleeve is slidably mounted on the forward working end 15 of the bucking bar and has an expanded rear portion i6 surroundinga'spring' Tl engaging forwardly at one end against a shoulder 18 in said sleeve and rearwardly against a shoulder 79 on said bucking bar at the other end and resiliently urging the sleeve forward to project beyond end or forward portion 15 of the bucking bar. 7

To prevent accidental loss or undue displacement of the sleeve, a retaining pin at is secured in the forward portion 75 ofthe bucking bar with the upper end extending into a longitudinal slot 82 in said sleeve and thus limiting movement of the latter to the extent allowed by the pin in said slot. An aperture 83 in the bottom of the sleeve affords access in one position of the latter to the lower end of the pin when the same is to heremoved for repairs or replacement of parts. Upon the rear of the enlarged portion 76 of the sleeve i4 is fixed a screw post 84 in which is mounted an adjustable screw 85 adapted to engage against th forward end 86 of the release slide member :58 in manual operating lever -52 in all positions of the bucking bar, it is obviously quite simple for the bucker to locate said end of the bar on the rivet without loss of time .or exercise of great care. When the device is moved toward the work I5 sufficiently to bring end 15 of bucking bar I8 into actual contact with the rivet as shown in Fig. 1, the sleeve 14 will be pushed in upon the bucking bar against th resistance of spring l1, and when the operator of said device depresses the manual lever52 from the position of Figs. 1 to 3 to that of Figs. 4 and 5, the contact of the lower strip 6| of release slide member 58 within or beneath the manual lever with the plunger or cap 49 will cause the latter to be depressed, and this in turn immediately opens the auxiliary valve 36 in casing 30 of the hammer. valv 24 having already been opened by the riveter, as already stated, the opening of valve 3 6 just mentioned immediately allows pressure fluid to flow to the piston ll of the hammer, and start actual operation of the latter. I

During this operation, as the riveting rapidly proceeds, the sleeve is gradually pushed further in upon the bucking bar by the latter following up the rogressive shortening of the rivet until the rivet has been completely set as shown at IT in Fig. 4. Such rearward movement 'of the sleeve is continuously transmitted to the release slide member 58 within lever 52 in opposition to spring 6! of the. latter and produces a corresponding rearward travel of said member 58 until the aperture E3 in the bottom of the same begins to registerwith the cable plunger 49. At this instant the mentioned plunger, urged by its spring'5l, immediately rises up into the aperture 13 directly above the same and by correspondingly pulling on the cable core 43, effects instant closure of auxiliary valve 36 in the hammer assembly and stops operation of the hammer. The time of subsequent closure of the throttle valve 24 by release of the'trigger l3 by the rivet is of minor importance in the cycle of operation just described, and the two devices are therefore shifted by both operators to a new rivet for setting the same in a new cycle of operation. 7

The hammering operation is thus terminated automatically when the front end 15 of the buck bar,l8 approaches within a pred'termined distance of the work I5 and of the front extremity of sleeve 14., This-distance, which corresponds to the height of the completed rivet, remains uniform'in successive operations as long as the elements of the device remain in their adjusted position. To increase (or decrease) the height of theffinished rivet, the adjustable screw is turned to a more rearward (or more forward) position in post 84.

A slightly different starting of the cycle is not only possible but occurrence thereof is also likely to be more or less frequent, for it may well be that the bucker is ready before the riveter and by haste or misinterpretation of a signal and with .the bucking mechanism in position, may depress the manual operating lever 52 to open valve 36 in the hammer mechanism before the latter is in position and thetrigger is pressed. by the The trigger operated throttle riveter to open throttle valve 24. Depressing said operating lever will not alone cause operation of the hammer, and will thus not occasion premature movement of any part of the assembly nor cause damage to the work piece involved, but actual operation is merely delayed until the riveter has the hammer anvil in place on the rivet head and then presses the trigger l3, when the hammer will operate and the cycle will proceed and be completed as previously described.

Manifestly, modifications are possible and may be resorted to, and parts may be altered in size or form and used without others, within the scope of the invention as defined in the appended claims.

What is claimed is:

1. A riveting assembly, comprising a fluid pres sure operated hammer, a bucking bar, said hammer and said bar being carried by separate operators and adapted to engage a rivet on opposite sides of the work, and means causing the operation of said hammer to be under the control of the hammer operator in dependence upon independently operable remote control from the buck:- ing bar in order to prevent damaging the rivet or the work by premature hammer operation, said means comprising a first fluid pressure control valve and local means associated with the hammer for opening said valve at will, a second fluid pressure control valve in series with said first valve and capable of being opened independently of the operation of the first valve, and mechanical operating means on said bucking bar capable of becoming automatically effective during operation to close said second valve upon production of a predetermined amount of set upon said rivet, said mechanical operating means on said bucking bar acting through a flexible cable comprising a sheath attached at one end to said hammer and at the other end to said bucking bar and containing a movable core extending into cooperative relation at one end with said auxiliary valve and at the other end extending to said hammer.

2. A riveting assembly, comprising a fluid pressure operated hammer, a bucking bar, said hammer and said bar being under separate control and adapted to engage a rivet on opposite sides of the work, supply means for conducting pressure fluid to said hammer, a throttle valve associated with said hammer for controlling the flow of pressure fluid through said supply means, an auxiliary valve for controlling the flow of fluid through the same supply means, said valves cooperating to cut off the flow of fluid to said hammer when either or both of said valves are closed, local operable means associated with said hamber for controlling said throttle valve, actuating means for said auxiliary valve including a flexible cable sheath extending between said hammer and said bucking bar and containing a movable core operable at one end as a movable plunger from said bucking bar and at the other end extending into cooperative relation with said auxiliary valve, operative means upon said bucking bar for moving said core and thereby opening said auxiliary valve, and movable means associated with said bucking bar capable of becoming automatically efiective to neutralize said operative means and release said core in order to cause said auxiliary valve to be closed upon completion of a predetermined degree of set upon said rivet.

3. In a riveting assembly, a bucking bar adapted for cooperation with a fluid pressure operated hammer, supply means for conducting pressure fluid to said hammer, a control valve associated with said hammer for controlling the flow of the fluid through said supply means to the hammer, actuating means for said control valve including a flexible cable comprising a core and a sheath surrounding the same, the core being movable with reference to the sheath upon the application of pressure to an end thereof having one actuating portion thereof extending into cooperative relation with said valve and having another actuating portion associated with the bucking bar and movable with respect thereto, operable means upon said bucking bar for imparting movement to said actuating means and thereby opening said control valve, and a movable releasing member supported upon said bucking bar automatically effective during operation to disable said operable means and release the motion transmitting means and thereby cause said control valve to be closed upon completion of a predetermined'amount of set upon said rivet.

4. A riveting assembly, comprising a fluid pressure operated hammer, a bucking bar, said hammer and said bar being carried by separate operators and adapted to engage a rivet on opposite sides of the work, supply means for conducting pressure fluid to said hammer, a throttle valve associated with said hammer for controlling the flow of fluid through said supply means, an auxiliary valve for controlling the flow of fluid through the same supply means, said valves cooperating to cut off the flow of fluid to said hammer when either or both of said valves are closed, local operable means associated with said hammer for controlling said throttle valve, actuating means for said auxiliary valve including a flexible motion transmitting means having one actuating portion extending into cooperative relation with said auxiliary valve and having another actuating portion associated with the bucking bar and movable with respect thereto, operable means upon said bucking bar for operating said motion transmitting means and thereby opening said valve, and a movable contacting member mounted on said bucking bar for engaging against the work in the vicinity of the rivet to be set, and a shiftable releasing member engaged by a portion of said contacting member and capable of neutralizing said operable means and releasing said motion transmitting means and thereby cause the auxiliary valve to be closed upon occurrence of a predetermined relative change in position between said bucking bar and contacting member caused during operation due to the progressive shortening of the rivet by the production of a predetermined amount of set upon said rivet.

5. A riveting assembly, comprising a fluid pressure operated hammer, a bucking bar, said hammer and said bar being carried by separate operators and adapted to engage a rivet on opposite sides of the Work, supply means for conducting pressure fluid to said hammer, a throttle valve associated with said hammer for controlling the flow of fluid through said supply means, an auxiliary valve for controlling the flow of fluid through the same supply means, said valves cooperating to cut off the flow of fluid to said hammer when either or both of said valves are closed, local operable means associated with said hammer for controlling said throttle valve, actuating means for said auxiliary valve including a flexible motion transmitting means having one end portion extending into cooperative relation with ible member-mounted in effective position to move a said other end portion of said motion transmitting means to open the auxiliary valve, resilient means tending to return said depressible member to initial position when released, a movable contact member slidably mounted upon said bucking bar for engaging against the Work, and a shiftable releasing member associated with said depressible member and engaged by a portion upon said contact member in effective position to be shifted relatively to said depressible member and neutralize the latter with consequent release of the motiontransmitting means and corresponding closure of the auxiliary valve upon currence of a predetermined relative change in position between said bucking bar and contact member due to the progressive shortening of the v rivet caused during operation by production of a predetermined amount of set upon said rivet.

6. In a riveting assembly, a bucking bar adapted for cooperation With a fluid pressure operated hammer, supply means for conducting pressure fluid to said hammer, a valve for controlling the flow of fluid through the supply means, actuating means for said valve including a flexible motion transmitting means having one end portion extending into cooperative relation with said valve and having the other end portion associated with the bucking bar and movable with respect thereto, manually operable means upon the buck ing bar including a depressib-le lever pivotally mounted in a position efiective to move said other a 10 means for said auxiliary valve including a flexible motion transmitting means having one end portion extending into cooperative relation with said auxiliary valve and having the other end portion associated with the bucking bar and movable With respect thereto, manually operable means upon the bucking bar including a depressible lever pivotally mounted in a position effective to move said other end portion of said motion transmitting means to open the auxiliary valve, resilient means tending to return said motion transmitting means in closing direction to initial position of said auxiliary valve, a movable contact member including a sleeve slidably mounted on said bucking bar, resilient means tending to cause a portion of said sleeve to project beyond the working end of the bucking bar to make direct contact with the work, resilient means also tending to returnsaid lever to initial position when released, a shiftable releasing member slidably mounted onsaid lever so as to partake of the pivoting movements thereof and normally allow the lever upon depression thereof to impart movement to the motion transmitting means and thereby cause opening of the auxiliary valve, and a projecting portion upon said slidably mounted sleeve engaging said releasing member at least end portion of said motion transmitting means to openthe valve, resilient means tending to return said motion transmitting means in closing direction to initial position of said valve to close the latter, a movable contact member slidably mounted on said bucking bar, resilient means tending to cause said contact member to'project beyond the working end-of the bucking bar to make clirect contact with the work,'said depressible lever also tending to be returned to initial position when released, and a shiftable releasing member associated with said depressible lever and engaged by a portion upon said contact member in effective position to be shifted relatively to said lever in order to neutralize the latter with consequent release of the motion transmiting means and closure of the valve upon occurrence during operation of a predetermined relative change in positions between said bucking bar and contact member due to the progressive shortening of the rivet caused by the production of a finished settingupon saidrivet.

7. A riveting assembly, comprising a fluid pressure operated hammer, a bucking bar, said hammer and said bar being carried by'separate operators and adapted to engage a rivet on cpposite sides of the work, supply means for conducting pressure fluid to said hammer, a throttle valve associated with said hammer for controlling the flow of fluid through said supply means;

an auxiliary valve for controlling the flow of fluid through the same supply means, said valves cooperating to cut off the flow of fluid to the hammer when either or both of said valves are closed, local operating means associated with said hammer forcontrolling said throttle valve, actuating in depressed. position of said lever and capable of neutralizing the effect of said lever in said depressed position with consequent release of the motion transmitting means and closure of the auxiliary valveupon occurrence of a predetermined change in relative positions between said sleeve. and bucking bardue to the progressive shortening of the rivet caused during operation by production of a predetermined degree of 'set upon said rivet.

8. A riveting assembly according to claim 7,

in which the releasing member is disposed within a porticnof, and carried by, the pivotally mounted lever and has one end thereof directed toward the pivoted end of the lever and engaged by the projecting sleeve portion serving as a reaction point for shifting said member.

9. A riveting assembly according to claim '7, in which the releasing member hasone end thereof disposed adjacent to the pivoted end of the lever and engaged by the projecting sleeve portion serving as a reaction point for shifting said member, and in which resilient means carried by the lever serves to urge said releasing member resiliently toward said projecting sleeve portion.

10. A riveting assembly according to claim '7, in which the releasing member normally forms the means upon the pivoted lever which directly engages with a projecting portion upon the end 7 of the motion transmitting means, and in which position of said releasing member, said gap portion releasing said motion transmitting means and allowing the same by entrance of the projecting end thereof into said gap portion to return to 'initial position and close the auxiliary valve.

11. A riveting assembly according to claim 7, in which stop means are included for limiting movement of the sleeve to a predetermined range, and in which the projecting portion on said sleeve includes an adjustable abutment member.

EDWARD w. STEVENS. 

